In a previous study from the biomarker laboratory of the University of Eastern Finland, patients without neurological diseases but with primary psychiatric disorders approximately 15 years older the MS patients in our study had similar NfL concentrations as the MS patients without Gd‐enhancing lesions of our study (Katisko, Cajanus, and Jääskeläinen (2020). Here, NEFL is linked to myeloid sarcoma.